<?php

/* !
 * Medoo database framework
 * http://medoo.in
 * Version 0.9.7
 * 
 * Copyright 2014, Angel Lai
 * Released under the MIT license
 */

class medoo {

    protected $dsn;
    protected $database_type;
    // For MySQL, MariaDB, MSSQL, Sybase, PostgreSQL, Oracle
    protected $server;
    protected $username;
    protected $password;
    // For SQLite
    protected $database_file;
    // For MySQL or MariaDB with unix_socket
    protected $socket;
    // Optional
    protected $port;
    protected $charset;
    protected $database_name;
    protected $option = array(
        //PDO::ATTR_PERSISTENT => true
    );
    protected $commands = array();
    // Variable 
    protected $logs = array();

    /**
     * 返回数据库实例
     */
    public static function getMasterInstance($options=null) {
        static $master_instance;
        //如果缓存中没有，则重新构造
        if (!isset($master_instance)) {
            $classname = __CLASS__;
            $master_instance = new $classname($options);
        }
        //返回结果
        return $master_instance;
    }

    public function __construct($options = null) {
        try {

            if (is_string($options) && !empty($options)) {
                if (strtolower($this->database_type) == 'sqlite') {
                    $this->database_file = $options;
                } else {
                    $this->database_name = $options;
                }
            } elseif (is_array($options)) {
                foreach ($options as $option => $value) {
                    $this->$option = $value;
                }
            }

            if (
                isset($this->port) &&
                is_int($this->port * 1)
            ) {
                $port = $this->port;
            }

            $type = strtolower($this->database_type);
            $is_port = isset($port);

            switch ($type) {
                case 'mariadb':
                    $type = 'mysql';

                case 'mysql':
                    if ($this->socket) {
                        $this->dsn = $type . ':unix_socket=' . $this->socket . ';dbname=' . $this->database_name;
                    } else {
                        $this->dsn = $type . ':host=' . $this->server . ($is_port ? ';port=' . $port : '') . ';dbname=' . $this->database_name;
                    }

                    // Make MySQL using standard quoted identifier
                    $this->commands[] = 'SET SQL_MODE=ANSI_QUOTES';
                    break;

                case 'pgsql':
                    $this->dsn = $type . ':host=' . $this->server . ($is_port ? ';port=' . $port : '') . ';dbname=' . $this->database_name;
                    break;

                case 'sybase':
                    $this->dsn = 'dblib:host=' . $this->server . ($is_port ? ':' . $port : '') . ';dbname=' . $this->database_name;
                    break;

                case 'oracle':
                    $dbname = $this->server ?
                        '//' . $this->server . ($is_port ? ':' . $port : ':1521') . '/' . $this->database_name :
                        $this->database_name;

                    $this->dsn = 'oci:dbname=' . $dbname . ($this->charset ? ';charset=' . $this->charset : '');
                    break;

                case 'mssql':
                    $this->dsn = strstr(PHP_OS, 'WIN') ?
                        'sqlsrv:server=' . $this->server . ($is_port ? ',' . $port : '') . ';database=' . $this->database_name :
                        'dblib:host=' . $this->server . ($is_port ? ':' . $port : '') . ';dbname=' . $this->database_name;

                    // Keep MSSQL QUOTED_IDENTIFIER is ON for standard quoting
                    $this->commands[] = 'SET QUOTED_IDENTIFIER ON';
                    break;

                case 'sqlite':
                    $this->dsn = $type . ':' . $this->database_file;
                    $this->username = null;
                    $this->password = null;
                    break;
            }

            if (
                in_array($type, explode(' ', 'mariadb mysql pgsql sybase mssql')) &&
                $this->charset
            ) {
                $this->commands[] = "SET NAMES '" . $this->charset . "'";
            }
            $this->connect();
        } catch (Exception $e) {
            throw new Exception($e->getMessage(), $e->getCode());
        }
    }

    public function connect($retry = 3) {

        try {
            $this->pdo = new PDO($this->dsn, $this->username, $this->password, $this->option);
            //$this->pdo = new pdo_connect_pool($this->dsn, $this->username, $this->password, $this->option);
            foreach ($this->commands as $value) {
                $this->pdo->exec($value);
            }
        } catch (PDOException $e) {
            if ($retry == 0) {
                SeasLog::error('数据库查询重连3次失败 ERR_MSG'.$e->getMessage());
                throw new Exception("数据库重连3次失败！" . $e->getMessage(), $e->getCode());
            }
            SeasLog::error('数据库查询失败SQL: ERR_MSG'.$e->getMessage());
            $this->connect( --$retry);
        }
    }

    public function __destruct() {
        //关闭连接 
        //$this->pdo->release();
        $this->pdo = NULL;
    }

    public function query($query, $retry = 3) {

        try {
            array_push($this->logs, $query);
            $result = $this->pdo->query($query);
        } catch (Exception $e) {
            if ($retry == 0) {
                SeasLog::error('数据库查询重连3次失败SQL:'.$query.' ERR_MSG'.$e->getMessage());
                throw new Exception("数据库查询重连3次失败！" . $e->getMessage(), $e->getCode());
            }

//            if($e->getCode() >= 2003 && $e->getCode() <= 2006){
                $this->connect();
//            }

            SeasLog::error('数据库查询失败SQL:'.$query.' ERR_MSG'.$e->getMessage());
            $result = $this->query($query, --$retry);
        }
        return $result;
    }

    public function exec($query, $retry = 3) {

        try {
            array_push($this->logs, $query);
            $result = $this->pdo->exec($query);
        } catch (PDOException $e) {
            if ($retry == 0) {
                SeasLog::error('数据库查询重连3次失败SQL:'.$query.' ERR_MSG'.$e->getMessage());
                throw new Exception("数据库执行重连3次失败！" . $e->getMessage(), $e->getCode());
            }
            SeasLog::error('数据库查询失败SQL:'.$query.' ERR_MSG'.$e->getMessage());

//            if($e->getCode() >= 2003 && $e->getCode() <= 2006){
                $this->connect();
//            }
//            $this->connect();//这里好像有个坑，如果在外面开启事务，如果有一次sql执行失败，这个connect会将连接重置，导致在commit或rollback的时候报错：There is no active transaction
            $result = $this->exec($query, --$retry);
        }
        return $result;
    }

    public function quote($string) {
        return $this->pdo->quote($string);
    }

    protected function column_quote($string) {
        return '"' . str_replace('.', '"."', preg_replace('/(^#|\(JSON\))/', '', $string)) . '"';
    }

    protected function column_push($columns) {
        if ($columns == '*') {
            return $columns;
        }

        if (is_string($columns)) {
            $columns = array($columns);
        }

        $stack = array();

        foreach ($columns as $key => $value) {
            preg_match('/([a-zA-Z0-9_\-\.]*)\s*\(([a-zA-Z0-9_\-]*)\)/i', $value, $match);

            if (isset($match[1], $match[2])) {
                array_push($stack, $this->column_quote($match[1]) . ' AS ' . $this->column_quote($match[2]));
            } else {
                array_push($stack, $this->column_quote($value));
            }
        }

        return implode($stack, ',');
    }

    protected function array_quote($array) {
        $temp = array();

        foreach ($array as $value) {
            $temp[] = is_int($value) ? $value : $this->pdo->quote($value);
        }

        return implode($temp, ',');
    }

    protected function inner_conjunct($data, $conjunctor, $outer_conjunctor) {
        $haystack = array();

        foreach ($data as $value) {
            $haystack[] = '(' . $this->data_implode($value, $conjunctor) . ')';
        }

        return implode($outer_conjunctor . ' ', $haystack);
    }

    protected function fn_quote($column, $string) {
        return (strpos($column, '#') === 0 && preg_match('/^[A-Z0-9\_]*\([^)]*\)$/', $string)) ?
            $string :
            $this->quote($string);
    }

    protected function data_implode($data, $conjunctor, $outer_conjunctor = null) {
        $wheres = array();

        foreach ($data as $key => $value) {
            $type = gettype($value);

            if (
                preg_match("/^(AND|OR)\s*#?/i", $key, $relation_match) &&
                $type == 'array'
            ) {
                $wheres[] = 0 !== count(array_diff_key($value, array_keys(array_keys($value)))) ?
                    '(' . $this->data_implode($value, ' ' . $relation_match[1]) . ')' :
                    '(' . $this->inner_conjunct($value, ' ' . $relation_match[1], $conjunctor) . ')';
            } else {
                preg_match('/(#?)([\w\.]+)(\[(\>|\>\=|\<|\<\=|\!|\<\>|\>\<|\!?~)\])?/i', $key, $match);
                $column = $this->column_quote($match[2]);

                if (isset($match[4])) {
                    $operator = $match[4];

                    if ($operator == '!') {
                        switch ($type) {
                            case 'NULL':
                                $wheres[] = $column . ' IS NOT NULL';
                                break;

                            case 'array':
                                $wheres[] = $column . ' NOT IN (' . $this->array_quote($value) . ')';
                                break;

                            case 'integer':
                            case 'double':
                                $wheres[] = $column . ' != ' . $value;
                                break;

                            case 'boolean':
                                $wheres[] = $column . ' != ' . ($value ? '1' : '0');
                                break;

                            case 'string':
                                $wheres[] = $column . ' != ' . $this->fn_quote($key, $value);
                                break;
                        }
                    }

                    if ($operator == '<>' || $operator == '><') {
                        if ($type == 'array') {
                            if ($operator == '><') {
                                $column .= ' NOT';
                            }

                            if (is_numeric($value[0]) && is_numeric($value[1])) {
                                $wheres[] = '(' . $column . ' BETWEEN ' . $value[0] . ' AND ' . $value[1] . ')';
                            } else {
                                $wheres[] = '(' . $column . ' BETWEEN ' . $this->quote($value[0]) . ' AND ' . $this->quote($value[1]) . ')';
                            }
                        }
                    }

                    if ($operator == '~' || $operator == '!~') {
                        if ($type == 'string') {
                            if ($operator == '!~') {
                                $column .= ' NOT';
                            }

                            if (preg_match('/^[^%].+[^%]$/', $value)) {
                                $value = '%' . $value . '%';
                            }

                            $wheres[] = $column . ' LIKE ' . $this->fn_quote($key, $value);
                        }
                    }

                    if (in_array($operator, array('>', '>=', '<', '<='))) {
                        if (is_numeric($value)) {
                            $wheres[] = $column . ' ' . $operator . ' ' . $value;
                        } else {
                            $datetime = strtotime($value);

                            if ($datetime) {
                                $wheres[] = $column . ' ' . $operator . ' ' . $this->quote(date('Y-m-d H:i:s', $datetime));
                            } else {
                                if (strpos($key, '#') === 0) {
                                    $wheres[] = $column . ' ' . $operator . ' ' . $this->fn_quote($key, $value);
                                }
                            }
                        }
                    }
                } else {
                    if (is_int($key)) {
                        $wheres[] = $this->quote($value);
                    } else {
                        switch ($type) {
                            case 'NULL':
                                $wheres[] = $column . ' IS NULL';
                                break;

                            case 'array':
                                $wheres[] = $column . ' IN (' . $this->array_quote($value) . ')';
                                break;

                            case 'integer':
                            case 'double':
                                $wheres[] = $column . ' = ' . $value;
                                break;

                            case 'boolean':
                                $wheres[] = $column . ' = ' . ($value ? '1' : '0');
                                break;

                            case 'string':
                                $wheres[] = $column . ' = ' . $this->fn_quote($key, $value);
                                break;
                        }
                    }
                }
            }
        }

        return implode($conjunctor . ' ', $wheres);
    }

    protected function where_clause($where) {
        $where_clause = '';

        if (is_array($where)) {
            $where_keys = array_keys($where);
            $where_AND = preg_grep("/^AND\s*#?$/i", $where_keys);
            $where_OR = preg_grep("/^OR\s*#?$/i", $where_keys);

            $single_condition = array_diff_key($where, array_flip(
                explode(' ', 'AND OR GROUP ORDER HAVING LIMIT LIKE MATCH')
            ));

            if ($single_condition != array()) {
                $where_clause = ' WHERE ' . $this->data_implode($single_condition, '');
            }

            if (!empty($where_AND)) {
                $value = array_values($where_AND);
                $where_clause = ' WHERE ' . $this->data_implode($where[$value[0]], ' AND');
            }

            if (!empty($where_OR)) {
                $value = array_values($where_OR);
                $where_clause = ' WHERE ' . $this->data_implode($where[$value[0]], ' OR');
            }

            // Will be deprecated
            if (isset($where['LIKE'])) {
                $LIKE = $where['LIKE'];

                if (is_array($LIKE)) {
                    $is_OR = isset($LIKE['OR']);
                    $clause_wrap = array();

                    if ($is_OR || isset($LIKE['AND'])) {
                        $connector = $is_OR ? 'OR' : 'AND';
                        $LIKE = $is_OR ? $LIKE['OR'] : $LIKE['AND'];
                    } else {
                        $connector = 'AND';
                    }

                    foreach ($LIKE as $column => $keyword) {
                        $keyword = is_array($keyword) ? $keyword : array($keyword);

                        foreach ($keyword as $key) {
                            preg_match('/(%?)([a-zA-Z0-9_\-\.]*)(%?)((\[!\])?)/', $column, $column_match);

                            if ($column_match[1] == '' && $column_match[3] == '') {
                                $column_match[1] = '%';
                                $column_match[3] = '%';
                            }

                            $clause_wrap[] = $this->column_quote($column_match[2]) .
                                ($column_match[4] != '' ? ' NOT' : '') . ' LIKE ' .
                                $this->quote($column_match[1] . $key . $column_match[3]);
                        }
                    }

                    $where_clause .= ($where_clause != '' ? ' AND ' : ' WHERE ') . '(' . implode($clause_wrap, ' ' . $connector . ' ') . ')';
                }
            }

            if (isset($where['MATCH'])) {
                $MATCH = $where['MATCH'];

                if (is_array($MATCH) && isset($MATCH['columns'], $MATCH['keyword'])) {
                    $where_clause .= ($where_clause != '' ? ' AND ' : ' WHERE ') . ' MATCH ("' . str_replace('.', '"."', implode($MATCH['columns'], '", "')) . '") AGAINST (' . $this->quote($MATCH['keyword']) . ')';
                }
            }

            if (isset($where['GROUP'])) {
                $where_clause .= ' GROUP BY ' . $this->column_quote($where['GROUP']);

                if (isset($where['HAVING'])) {
                    $where_clause .= ' HAVING ' . $this->data_implode($where['HAVING'], ' AND');
                }
            }

            if (isset($where['ORDER'])) {
                $rsort = '/(^[a-zA-Z0-9_\-\.]*)(\s*(DESC|ASC))?/';
                $ORDER = $where['ORDER'];

                if (is_array($ORDER)) {
                    if (
                        isset($ORDER[1]) &&
                        is_array($ORDER[1])
                    ) {
                        $where_clause .= ' ORDER BY FIELD(' . $this->column_quote($ORDER[0]) . ', ' . $this->array_quote($ORDER[1]) . ')';
                    } else {
                        $stack = array();

                        foreach ($ORDER as $column) {
                            preg_match($rsort, $column, $order_match);

                            array_push($stack, '"' . str_replace('.', '"."', $order_match[1]) . '"' . (isset($order_match[3]) ? ' ' . $order_match[3] : ''));
                        }

                        $where_clause .= ' ORDER BY ' . implode($stack, ',');
                    }
                } else {
                    preg_match($rsort, $ORDER, $order_match);

                    $where_clause .= ' ORDER BY "' . str_replace('.', '"."', $order_match[1]) . '"' . (isset($order_match[3]) ? ' ' . $order_match[3] : '');
                }
            }

            if (isset($where['LIMIT'])) {
                $LIMIT = $where['LIMIT'];

                if (is_numeric($LIMIT)) {
                    $where_clause .= ' LIMIT ' . $LIMIT;
                }

                if (
                    is_array($LIMIT) &&
                    is_numeric($LIMIT[0]) &&
                    is_numeric($LIMIT[1])
                ) {
                    $where_clause .= ' LIMIT ' . $LIMIT[0] . ',' . $LIMIT[1];
                }
            }
        } else {
            if ($where != null) {
                $where_clause .= ' ' . $where;
            }
        }

        return $where_clause;
    }

    protected function select_context($table, $join, &$columns = null, $where = null, $column_fn = null) {
        $table = '"' . $table . '"';
        $join_key = is_array($join) ? array_keys($join) : null;

        if (
            isset($join_key[0]) &&
            strpos($join_key[0], '[') === 0
        ) {
            $table_join = array();

            $join_array = array(
                '>' => 'LEFT',
                '<' => 'RIGHT',
                '<>' => 'FULL',
                '><' => 'INNER'
            );

            foreach ($join as $sub_table => $relation) {
                preg_match('/(\[(\<|\>|\>\<|\<\>)\])?([a-zA-Z0-9_\-]*)\s?(\(([a-zA-Z0-9_\-]*)\))?/', $sub_table, $match);

                if ($match[2] != '' && $match[3] != '') {
                    if (is_string($relation)) {
                        $relation = 'USING ("' . $relation . '")';
                    }

                    if (is_array($relation)) {
                        // For ['column1', 'column2']
                        if (isset($relation[0])) {
                            $relation = 'USING ("' . implode($relation, '", "') . '")';
                        }
                        // For ['column1' => 'column2']
                        else {
//                             $relation = 'ON ' . $table . '."' . key($relation) . '" = "' . (isset($match[5]) ? $match[5] : $match[3]) . '"."' . current($relation) . '"';

                            /*
                             *  If the key looks like `___.___` (. as delimiter between table and column)
                            *  => Don't need the $table variable
                            */
                            $splitted_key_relation = explode('.', key($relation));
                            if (count($splitted_key_relation) == 2) {
                                $key_relation = implode('"."',$splitted_key_relation);
                                $relationQuery  = 'ON "' . $key_relation . '" = "';
                                $relationQuery .= (isset($match[5]) ? $match[5] : $match[3]) . '"."' . current($relation) . '"';
                                $relation = $relationQuery;
                            } else {
                                $relationQuery  = 'ON ' . $table . '."' . key($relation) . '" = "';
                                $relationQuery .= (isset($match[5]) ? $match[5] : $match[3]) . '"."' . current($relation) . '"';
                                $relation = $relationQuery;
                            }
                        }
                    }

                    $table_join[] = $join_array[$match[2]] . ' JOIN "' . $match[3] . '" ' . (isset($match[5]) ? 'AS "' . $match[5] . '" ' : '') . $relation;
                }
            }

            $table .= ' ' . implode($table_join, ' ');
        } else {
            if (is_null($columns)) {
                if (is_null($where)) {
                    if (
                        is_array($join) &&
                        isset($column_fn)
                    ) {
                        $where = $join;
                        $columns = null;
                    } else {
                        $where = null;
                        $columns = $join;
                    }
                } else {
                    $where = $join;
                    $columns = null;
                }
            } else {
                $where = $columns;
                $columns = $join;
            }
        }

        if (isset($column_fn)) {
            if ($column_fn == 1) {
                $column = '1';

                if (is_null($where)) {
                    $where = $columns;
                }
            } else {
                if (empty($columns)) {
                    $columns = '*';
                    $where = $join;
                }

                $column = $column_fn . '(' . $this->column_push($columns) . ')';
            }
        } else {
            $column = $this->column_push($columns);
        }

        return 'SELECT ' . $column . ' FROM ' . $table . $this->where_clause($where);
    }

    public function select($table, $join, $columns = null, $where = null) {
        $query = $this->query($this->select_context($table, $join, $columns, $where));

        return $query ? $query->fetchAll(
            (is_string($columns) && $columns != '*') ? PDO::FETCH_COLUMN : PDO::FETCH_ASSOC
        ) : false;
    }

    public function insert($table, $datas,$hasPk=false) {
        $lastId = array();

        // Check indexed or associative array
        if (!isset($datas[0])) {
            $datas = array($datas);
        }

        foreach ($datas as $data) {
            $keys = array_keys($data);
            $values = array();
            $columns = array();

            foreach ($data as $key => $value) {
                array_push($columns, $this->column_quote($key));

                switch (gettype($value)) {
                    case 'NULL':
                        $values[] = 'NULL';
                        break;

                    case 'array':
                        preg_match("/\(JSON\)\s*([\w]+)/i", $key, $column_match);

                        $values[] = isset($column_match[0]) ?
                            $this->quote(json_encode($value)) :
                            $this->quote(serialize($value));
                        break;

                    case 'boolean':
                        $values[] = ($value ? '1' : '0');
                        break;

                    case 'integer':
                    case 'double':
                    case 'string':
                        $values[] = $this->fn_quote($key, $value);
                        break;
                }
            }

            $flag = $this->exec('INSERT INTO "' . $table . '" (' . implode(', ', $columns) . ') VALUES (' . implode($values, ', ') . ')');
            if($hasPk){
                $lastId[] = $flag;
            }else{
                $lastId[] = $this->pdo->lastInsertId();
            }
        }

        return count($lastId) > 1 ? $lastId : $lastId[0];
    }

    public function update($table, $data, $where = null) {
        $fields = array();

        foreach ($data as $key => $value) {
            preg_match('/([\w]+)(\[(\+|\-|\*|\/)\])?/i', $key, $match);

            if (isset($match[3])) {
                if (is_numeric($value)) {
                    $fields[] = $this->column_quote($match[1]) . ' = ' . $this->column_quote($match[1]) . ' ' . $match[3] . ' ' . $value;
                }
            } else {
                $column = $this->column_quote($key);

                switch (gettype($value)) {
                    case 'NULL':
                        $fields[] = $column . ' = NULL';
                        break;

                    case 'array':
                        preg_match("/\(JSON\)\s*([\w]+)/i", $key, $column_match);

                        $fields[] = isset($column_match[0]) ?
                            $this->column_quote($column_match[1]) . ' = ' . $this->quote(json_encode($value)) :
                            $column . ' = ' . $this->quote(serialize($value));
                        break;

                    case 'boolean':
                        $fields[] = $column . ' = ' . ($value ? '1' : '0');
                        break;

                    case 'integer':
                    case 'double':
                    case 'string':
                        $fields[] = $column . ' = ' . $this->fn_quote($key, $value);
                        break;
                }
            }
        }

        return $this->exec('UPDATE "' . $table . '" SET ' . implode(', ', $fields) . $this->where_clause($where));
    }

    public function delete($table, $where) {
        return $this->exec('DELETE FROM "' . $table . '"' . $this->where_clause($where));
    }

    public function replace($table, $columns, $search = null, $replace = null, $where = null) {
        if (is_array($columns)) {
            $replace_query = array();

            foreach ($columns as $column => $replacements) {
                foreach ($replacements as $replace_search => $replace_replacement) {
                    $replace_query[] = $column . ' = REPLACE(' . $this->column_quote($column) . ', ' . $this->quote($replace_search) . ', ' . $this->quote($replace_replacement) . ')';
                }
            }

            $replace_query = implode(', ', $replace_query);
            $where = $search;
        } else {
            if (is_array($search)) {
                $replace_query = array();

                foreach ($search as $replace_search => $replace_replacement) {
                    $replace_query[] = $columns . ' = REPLACE(' . $this->column_quote($columns) . ', ' . $this->quote($replace_search) . ', ' . $this->quote($replace_replacement) . ')';
                }

                $replace_query = implode(', ', $replace_query);
                $where = $replace;
            } else {
                $replace_query = $columns . ' = REPLACE(' . $this->column_quote($columns) . ', ' . $this->quote($search) . ', ' . $this->quote($replace) . ')';
            }
        }

        return $this->exec('UPDATE "' . $table . '" SET ' . $replace_query . $this->where_clause($where));
    }

    public function get($table, $join = null, $column = null, $where = null) {
        if (!isset($where)) {
            $where = array();
        }

        $where['LIMIT'] = 1;

        $query = $this->query($this->select_context($table, $join, $column, $where));

        $data = null;
        if($query){

            $data = $query->fetchAll(PDO::FETCH_ASSOC);
        }else{

            SeasLog::warning('没有找到结果SQl:'.$this->last_query());
        }

        if (isset($data[0])) {
            $column = $where == null ? $join : $column;

            if (is_string($column) && $column != '*') {
                return $data[0][$column];
            }

            return $data[0];
        } else {
            return false;
        }
    }

    public function has($table, $join, $where = null) {
        $column = null;

        return $this->query('SELECT EXISTS(' . $this->select_context($table, $join, $column, $where, 1) . ')')->fetchColumn() === '1';
    }

    public function count($table, $join = null, $column = null, $where = null) {
        return 0 + ($this->query($this->select_context($table, $join, $column, $where, 'COUNT'))->fetchColumn());
    }

    public function max($table, $join, $column = null, $where = null) {
        $max = $this->query($this->select_context($table, $join, $column, $where, 'MAX'))->fetchColumn();

        return is_numeric($max) ? $max + 0 : $max;
    }

    public function min($table, $join, $column = null, $where = null) {
        $min = $this->query($this->select_context($table, $join, $column, $where, 'MIN'))->fetchColumn();

        return is_numeric($min) ? $min + 0 : $min;
    }

    public function avg($table, $join, $column = null, $where = null) {
        return 0 + ($this->query($this->select_context($table, $join, $column, $where, 'AVG'))->fetchColumn());
    }

    public function sum($table, $join, $column = null, $where = null) {
        return 0 + ($this->query($this->select_context($table, $join, $column, $where, 'SUM'))->fetchColumn());
    }

    public function error() {
        return $this->pdo->errorInfo();
    }

    public function last_query() {
        return end($this->logs);
    }

    public function log() {
        return $this->logs;
    }

    public function info() {
        $output = array(
            'server' => 'SERVER_INFO',
            'driver' => 'DRIVER_NAME',
            'client' => 'CLIENT_VERSION',
            'version' => 'SERVER_VERSION',
            'connection' => 'CONNECTION_STATUS'
        );

        foreach ($output as $key => $value) {
            $output[$key] = $this->pdo->getAttribute(constant('PDO::ATTR_' . $value));
        }

        return $output;
    }

}

?>